I need your advice to help my girls...pics

This is my 5th indoor grow in a well ventilated 3X6 closet. I am a month into 12/12. I am using a neautral grow medimum with Fox farm neuts with a 400 w hps lamp. My watering schedule is every 3 or 4 days. Yesterday everything was good but today on several of my top buds on several plants the fan leaves are curling up and drying. Never seen this before?? My first reaction was over feeding so I flushed all the plants. Just wondering whats going on and how can I fix it if possible

You sure they arent to hot as well as overfed?
Do you have a fan moving the air across the tops?

looks to be too hot. i agree with natmoon. But i have never seen the leaves curl that much.

Make sure you check the ph of both your water and your soil runoff......

either too hot or too humid? could also be magnesium (Mg) deficiency caused by too low pH.

u started another one?
https://www.rollitup.org/marijuana-plant-problems/33576-help-am-i-going-loose.html???

Funny thing is only 2 of my 5 are showing this problem. Ventiliation is good...temp is good (79-85) and humity is good( not over 50%). I really think heat is not the issue. Lights are 12 to 14 in away from tops....but I never thought about a fan blowing on the tops.

what's the pH?

bing bing bing there u have it get a fan blowin on those heads and it should go away if not slowly back the light away

ph is parts hydrogen it shows how acidic ur soil or nutes ect are